Abstract: The invention relates to a fuel cell stack comprising a base plate supporting fuel cells and a cap of an electrically insulating material, particularly of ceramics, for electrically insulating the fuel cells stacked on top of each other partially enveloping the fuel cells stacked on top of each other. According to the invention it is contemplated that a metal cap provided for guiding cathode gas envelops the cap including the fuel cells together with the base plate and that the metal cap is attached to the base plate in a sealed manner. The invention further relates to a method for producing a fuel cell stack.

Abstract: The Intention relates to a fuel cell system comprising a reformer with a burner unit for reacting fuel with oxidant in an exothermic oxidation reaction to form a product gas which downstream of the burner unit is mixable with additional fuel, the resulting gas mixture being reformable in the reformer into a reformate; a fuel cell stack for receiving a supply of the reformate; and an afterburner for receiving a supply of the substances reacted in the fuel cell stack, with a burner unit for reacting fuel with oxidant in an exothermic oxidation reaction. In accordance with the invention it is provided for the burner unit of the reformer is engineered identical to the burner unit of the afterburner. In addition, the invention relates to a motor vehicle comprising one such fuel cell system.

Abstract: The invention relates to a fuel cells system (10) which comprises at least one heat-generating component (12 to 32) and at least one component (12, 14, 16) that uses process air. The invention is characterized in that ambient air (34) can be supplied to the heat-generating component, said air being heatable by the heat-generating component (12 to 32), and the air heated in said manner being supplied to the component (12, 14, 16) that uses process air. The invention also relates to a method for influencing the thermal balance of the fuel cell system according to the invention.

Abstract: The invention relates to a fuel cell stack comprising a base plate supporting fuel cells and a cap of an electrically insulating material, particularly of ceramics, for electrically insulating the fuel cells stacked on top of each other partially enveloping the fuel cells stacked on top of each other. According to the invention it is contemplated that a metal cap provided for guiding cathode gas envelops the cap including the fuel cells together with the base plate and that the metal cap is attached to the base plate in a sealed manner. The invention further relates to a method for producing a fuel cell stack.

Abstract: The invention relates to a fuel cell system (10) which comprises a reformer (12) having an oxidation zone (48) to which stored fuel can be supplied by means of a fuel supply device (50) for reaction with an oxidant; and an afterburner (36) having an oxidation zone (60) to which stored fuel can be supplied by means of a fuel supply device (62) for reaction with an oxidant. The invention is characterized in that the fuel supply device (50) of the reformer (12) and the fuel supply device (62) of the afterburner (36) are adapted to supply fuel in such a manner that the fuel supplied by the fuel supply device (50) of the reformer differs from the fuel supplied by the fuel supply device (62) of the afterburner (36) with respect to the type of fuel and/or its state of aggregation and/or the temperature at which it is supplied. The invention also relates to a motor vehicle comprising said fuel cell system and to a method for operating said fuel cell system.

Abstract: The invention relates to a reformer (12) for a fuel cell system (10). Said reformer comprises an oxidation zone (48) to which stored fuel can be supplied by means of a primary fuel supply device (50; 62) for reaction with an oxidant; and a mixing zone (54), arranged downstream of the oxidation zone (48), to which stored fuel can be supplied by means of a secondary fuel supply device (56; 64) for mixing with substances originating from the oxidation zone (48). The invention is characterized in that the primary fuel supply device (50; 62) and the secondary fuel supply device (56; 64) are adapted to supply fuel in such a manner that the fuel supplied by the primary fuel supply device (50; 62) differs from the fuel supplied by the secondary fuel supply device (56; 64) with respect to the type of fuel and/or its state of aggregation and/or the pressure and/or the temperature at which it is supplied.

Abstract: The invention relates to a method for regenerating a reformer fed with a mixture of fuel and an oxidant having a mean air number ?1 in continuous reformer operation, the air number being varied for the purpose of regenerating the reformer. In accordance with the invention it is provided for that regeneration occurs in a shutoff phase of the reformer in that the reformer is operated during several successive time intervals with an air number ?2 higher than in reformer operation (?2>?1). Again in accordance with the invention it may be provided for that regeneration occurs in a starting phase of the reformer in that the reformer is continually operated with an air number increased as compared to reformer operation ?2>?1 until a critical temperature threshold is attained. The invention relates furthermore to a system including a reformer and a controller for implementing a method in accordance with the invention.

Abstract: The invention relates to a method for diagnosing a condition of a reformer (16) in a fuel cell system. In accordance with the invention it is provided for that diagnosing the condition of the reformer (16) is performed on the basis of one or more predefined characteristics correlating with an conversion degree.

Abstract: The invention relates to a method of starting up a fuel cell system comprising a reformer (10) and a fuel cell stack (12), the reformer receiving during a first start-up phase a supply of oxygen and fuel with a first air ratio ?i characterizing the fuel/air ratio, the reformer receiving during a second start-up phase a supply of oxygen and fuel with a second air ratio ?2 characterizing the fuel/air ratio, the first fuel/air ratio ?1 being larger than the second air ratio ?2 (?1>?2) and the fuel cell stack receiving a supply of reformate (18) generated in the reformer during the first and the second start-up phase. In accordance with the invention it is provided for that the transition from the first start-up phase to the second start-up phase is monitored by sensing a voltage furnished by the fuel cell stack (12). The invention relates furthermore to a fuel cell system.

Abstract: The invention relates to a fuel cell system including a first heat exchanger via which cathode feed air can be supplied to a fuel cell or fuel cell stack and to which a mixture of afterburner exhaust gas of an afterburner and cathode exhaust air having materialized in the fuel cell or fuel cell stack can be supplied for heat exchange between the cathode feed air and the mixture via the first heat exchanger. In accordance with the invention it is provided for that a second heat exchanger is provided via which the cathode feed air can be supplied from the first heat exchanger to the fuel cell or fuel cell stack and via which the afterburner exhaust gas can be supplied to the first heat exchanger to form the mixture, in thus achieving a heat exchange between the afterburner exhaust gas and the cathode feed air.

Abstract: The invention relates to a reformer system for generating a hydrogen-rich reformate comprising a reformer to which fuel and an oxidising agent can be supplied. According to the invention it is contemplated that the fuel supplied to the reformer is at least partly coolable by a fluid having other functions in addition to the function of cooling the fuel in the reformer system or a parent system into which the reformer system is integrated. The invention further relates to a method for generating a hydrogen-rich reformate as well as a fuel cell system comprising a reformer system according to the invention.

Abstract: The invention relates to a method of starting up a fuel cell system comprising a reformer (10) and a fuel cell stack (12), the reformer receiving a supply of fuel (14) and air (16) as the starting materials and the fuel cell stack receiving a supply of reformate (18) generated by the reformer. In accordance with the invention it is provided for that the air ratio characterizing the fuel/air ratio of the starting materials supplied to the reformer (10) is varied as a function of a temperature of the fuel cell stack (12). The invention relates furthermore to a fuel cell system.

Abstract: The invention relates to a fuel cell system comprising a re-former (10) for reacting fuel (12) and oxidizer (14) so as to obtain reformate (16) as well as at least one fuel cell (18) to which reformate (16) is fed. The reformer (10) is fitted with a reformer burier (20) and a reformer catalyst (22). Means (24) for feeding anode exhaust gas (26) of the fuel cell (18) and/or reformate (16) and/or exhaust gas (28) of an afterburner (30) mounted downstream from the fuel cell (18) are provided between the reformer burner (20) and the reformer catalyst (22). The invention also relates to a method for operating a reformer (10) to react fuel (12) and oxidizer (14) so as to obtain reformate (16).

Abstract: The invention relates to a method for closed/open loop control of a total lambda value of a reformer (10) comprising at least a combustion zone (12) and an evaporation zone (14) connected to the combustion zone (12). In accordance with the invention for closed/open loop control of the total lambda value, closed loop control of the lambda value of the combustion zone (12) and open loop control of the fuel performance supplied to the evaporation zone (14) is provided. The invention relates furthermore to a system with a reformer (10) comprising at least a combustion zone (12) and an evaporation zone (14) connected to the combustion zone (12) and with a a controller (26) for closed/open loop control of a total lambda value.

Abstract: The invention relates to a process for determining the lambda value (?actual) of reformate provided for supply to a fuel cell stack, in which the no-load voltage across at least one fuel cell element is detected and evaluated for determining the lambda value (?actual). In accordance with the invention it is provided for that the at least one fuel cell element is a terminal fuel cell element of the fuel cell stack exclusively provided for sensing, and the voltage provided for at least one consumer can be picked off across the remaining fuel cell elements of the fuel cell stack. The invention relates furthermore to a process for lambda control of a reformer, a device for determining the lambda value, as well as to a system comprising a reformer for reacting at least fuel and air into reformate, and a fuel cell stack which is connected with the reformer for receiving reformate therefrom, the reformer being lambda-controlled.

Abstract: The invention relates to a reformer for a fuel cell system for generating a reformate comprising a plurality of function units for treating the fuel, at least one function unit being adapted to a first type of fuel. In this arrangement the invention is characterized to advantage in that the function unit adapted to the first type of fuel can be releasably coupled to the reformer as a module by means of an interface which is also designed to couple a replacement function unit instead of the function unit adapted to the first type of fuel, the replacement function unit being adapted to a second type of fuel different from the first type of fuel. The invention relates furthermore to a function unit for such a reformer, to a fuel cell system having such a reformer and to a motor vehicle having such a fuel cell system.

Abstract: The invention relates to a fuel cell system including a fuel cell stack (10), an afterburner (12) for combustion of exhaust gas emerging from the fuel cell stack and sited in an exhaust gas conduit of the afterburner a heat exchanger (16) in which cathode feed air (18) supplied to the fuel cell stack (10) can be heated. In accordance with the invention it is provided for that cathode feed air (20) can be supplied to the fuel cell stack (10) without being prior heated in the heat exchanger (16) and that the heat and temperature balance of the fuel cell stack (10) can be tweaked by the overall flow of the cathode feed air supplied as well as by the ratio of the proportions (18, 20) of the cathode feed air as heated in the heat exchanger and as not heated in the heat exchanger. The invention relates furthermore to a method of tweaking the heat and temperature balance of a fuel cell stack.

Abstract: The invention relates to a fuel cell system comprising a reformer and an afterburner each for reacting at least fuel and an oxidant; and a fuel feeder for supplying the reformer and the afterburner with fuel. It is provided for to particular advantage that at least one flow control valve for controlling the fuel supply is included upstream of at least the reformer or the afterburner. The invention relates furthermore to a motor vehicle having one such fuel cell system.

Abstract: The present invention relates to a gas sensor for determining the concentration of a gas component of a measurement gas and especially of a measurement gas formed by a combustion or reforming process. The gas sensor includes a layer structure and comprises a reference electrode and a catalytically active working electrode for exposure to the measurement gas. The reference electrode is completely surrounded by a gastight material.

Abstract: System and process for producing a reformate to be supplied to a fuel cell stack, the system having a reformer (12) to which fuel (14), air (16) and the anode exhaust gas (18) of the fuel cell stack can be supplied to produce the reformate (10). The system has one or more devices (20) which at least partially oxidize the anode exhaust gas (18) before it is supplied to the reformer (12).